Radiotherapy: could it sometimes do more harm than good?

Could radiotherapy do more harm than good in some patients?

radiotherapy machine image
A new study is looking at whether radiotherapy could lead to a type of cell, known as Langerhans cells, reducing the immune system’s ability to fight cancers, such as skin cancer.

2015 Study abstract

Treatment with ionizing radiation (IR) can lead to the accumulation of tumor-infiltrating regulatory T cells (Treg cells) and subsequent resistance of tumors to radiotherapy. Here we focused on the contribution of the epidermal mononuclear phagocytes Langerhans cells (LCs) to this phenomenon because of their ability to resist depletion by high-dose IR. We found that LCs resisted apoptosis and rapidly repaired DNA damage after exposure to IR. In particular, we found that the cyclin-dependent kinase inhibitor CDKN1A (p21) was overexpressed in LCs and that Cdkn1a−/− LCs underwent apoptosis and accumulated DNA damage following IR treatment. Wild-type LCs upregulated major histocompatibility complex class II molecules, migrated to the draining lymph nodes and induced an increase in Treg cell numbers upon exposure to IR, but Cdkn1a−/− LCs did not. Our findings suggest a means for manipulating the resistance of LCs to IR to enhance the response of cutaneous tumors to radiotherapy.

Sources and more information
  • CDKN1A regulates Langerhans cell survival and promotes Treg cell generation upon exposure to ionizing irradiation, Nature Immunology, doi:10.1038/ni.3270, 07 September 2015.
  • Could radiotherapy do more harm than good in some patients? dailymail, 7 September 2015.

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